Shell slender, ovate, twice as long as broad, with deep sagittal stricture and complete ring. Network very delicate, with very small and numerous triangular pores (on both poles intermingled with irregular polygonal pores). The two large apical holes are separated by a latticed triangular sagittal septum, the upper edge of which is concave and bears two rudimentary horns. Basal plate with four large collar holes. Three feet latticed, slightly curved, convergent, scarcely one-eighth as long as the breadth of the shell. The central capsule filled up by concrements. _Dimensions._--Shell 0.32 long, 0.16 broad. _Habitat._--Central Pacific, Station 271, depth 2425 fathoms. 3. _Cephalospyris triangulata_, n. sp. (Pl. 96, fig. 28). Shell ovate, one and a half times as long as broad, with deep sagittal stricture and complete ring. Network very delicate and regular, with small triangular pores of equal size. The two large apical holes are separated by a latticed semilunar septum, the upper edge of which is concave, and bears two rudimentary horns. Basal plate with three large collar holes (?). Three feet latticed, conical, nearly parallel and vertical (the caudal curved), about half as long as the breadth of the shell. The ovate central capsule contains peculiar amyloidal concentric concrements. _Dimensions._--Shell 0.2 long, 0.14 broad. _Habitat._--Central Pacific, Station 274, depth 2750 fathoms. Subfamily 2. DIPOSPYRIDA, Haeckel, 1881, Prodromus, p. 441. _Definition._--#Zygospyrida# dipoda, with two descending lateral basal feet (probably corresponding to the pectoral feet of _Cortina_). {1036}Genus 445. _Dipospyris_,[63] Haeckel, 1881, Prodromus, p. 441. _Definition._--#Zygospyrida# with two simple free basal feet and one apical horn. The genus _Dipospyris_ and the following five genera represent together the interesting subfamily of Dipospyrida, which always bear two opposite lateral feet only. Therefore in this bipedal group the biradial or bilateral type of the #Spyroidea# is particularly expressed. Such bipedal forms never occur in the #Cyrtoidea#. The topographical relation of the two lateral feet to the rods of the collar-plate, and to the cortinar pores separated by these, leaves no doubt that they correspond to the pectoral feet of _Cortina_ and _Tripospyris_, and therefore that the Dipospyrida have originated from the Tripospyrida by loss of the caudal foot. _Dipospyris_ is the simplest form of the Dipospyrida, with two simple free feet. 1. _Dipospyris bipes_, n. sp. Shell thorax-shaped, smooth, with deep sagittal stricture, two vaulted bosoms, and subregular circular pores. Basal plate with two large collar pores only. Horn and feet equal, conical, straight, about as long as the shell; the feet widely divergent. _Dimensions._--Shell 0.08 long, 0.12 broad; horn and feet 0.1 to 0.15 long. _Habitat._--Fossil in Barbados. 2. _Dipospyris mystax_, Haeckel.